Condensed Consolidating Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities	$ 533,335	$ 358,006
Cash flows from investing activities
Additions to property, plant and equipment	(767,876)	(811,111)
Purchase of compression assets	(159,210)
Investments in unconsolidated affiliates	(286,267)	(425,298)
Proceeds from sale of assets	21,190	72,408
Net cash used in investing activities	(1,192,163)	(1,164,001)
Cash flows from financing activities
Proceeds from long-term borrowings	1,881,771	1,445,500
Payments on long-term debt borrowings	(1,759,771)	(1,340,700)
Proceeds from issuance of common units	52,155	399,812
Proceeds from issuance of senior notes	750,000	414,094
Distributions to unitholders	(390,615)	(275,199)
Capital contributions from noncontrolling interests	143,775	120,594
Payments on capital lease obligations	(2,591)	0
Debt issuance costs	(8,929)	(11,735)
Other	3,665	8,598
Net cash provided by financing activities	669,460	760,964
Net increase (decrease) in cash and cash equivalents	10,632	(45,031)
Cash and cash equivalents, beginning of period	17,229	64,994
Cash and cash equivalents, end of period	27,861	19,963
Eliminations
Cash flows from financing activities
Payments on capital lease obligations		0
Parent | Reportable Legal Entities
Cash flows from financing activities
Proceeds from issuance of common units	52,155	399,812
Proceeds from issuance of senior notes	750,000	414,094
Distributions to unitholders	(390,615)	(275,199)
Payments on capital lease obligations		0
Debt issuance costs	(8,929)	(6,286)
Other	3,665	8,598
Intercompany advances, net	(406,276)	(541,019)
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities	450,610	329,001
Cash flows from investing activities
Additions to property, plant and equipment	(346,924)	(496,602)
Purchase of compression assets	(159,210)
Investments in unconsolidated affiliates	(286,267)	(425,298)
Proceeds from sale of assets	21,099	72,408
Net cash used in investing activities	(771,302)	(849,492)
Cash flows from financing activities
Proceeds from long-term borrowings	1,881,771	1,445,500
Payments on long-term debt borrowings	(1,759,771)	(1,340,700)
Payments on capital lease obligations	(2,591)	0
Debt issuance costs		(5,449)
Intercompany advances, net	200,890	357,331
Net cash provided by financing activities	320,299	456,682
Net increase (decrease) in cash and cash equivalents	(393)	(63,809)
Cash and cash equivalents, beginning of period	400	63,216
Cash and cash equivalents, end of period	7	(593)
Non-Guarantors | Reportable Legal Entities
Cash flows from operating activities	82,725	29,005
Cash flows from investing activities
Additions to property, plant and equipment	(420,952)	(314,509)
Proceeds from sale of assets	91
Net cash used in investing activities	(420,861)	(314,509)
Cash flows from financing activities
Capital contributions from noncontrolling interests	143,775	120,594
Payments on capital lease obligations		0
Intercompany advances, net	205,386	183,688
Net cash provided by financing activities	349,161	304,282
Net increase (decrease) in cash and cash equivalents	11,025	18,778
Cash and cash equivalents, beginning of period	16,829	1,778
Cash and cash equivalents, end of period	$ 27,854	$ 20,556